The objective of this work is to understand the events that take place during a non-lethal selection for mutation that increase the cells metabolic capability. Specifically, we will study a selection for alterations which allow the uptake of large maltodextrins across the outer membrane of the bacterium Escherichia coli. We will determine what parameters influence the selection and if the selection itself influences the type of mutations that we obtain. We will biochemically and genetically characterize the events that occur during the long period of stationary growth on solid media that occurs during non-lethal selections. We will determine if the selection results in induction of stress response systems. And we will determine if starvation stress induces mutagenesis. Finally, we will attempt to determine the basis for the selection biases that occur. The knowledge gained from this work will help to clarify the nature of the events and forces that influence how cells respond to non- lethal selections for enhanced growth ability.
